The interventional radiology, also called interventional therapeutics, is a new subject developed in recent years by combining imaging diagnosis with clinic treatment. It is a generic term of several technologies for mini-invasive treatment through the guiding and monitoring by imaging device including digital subtraction angiography, CT, ultrasonic and magnetic resonance using puncture needle, catheter and other interventional equipment to guide specific equipment to a location of lesion through human body natural orifice and cavity or mini-wound. The common catheters are plastic pipes with a certain length at one end; the leading end is converging so as to be easily inserted into blood vessels and the tail end is consistent with that of the needle so as to be easily connected with an injector. The shape of the leading ends of the common catheters comprise, for example, a single arc, an anti-arc, a double-arc, a improved double-arc, liver arc anterior view, liver arc lateral view, three arcs and the like so as to be easily inserted into blood vessels at different parts. Specification of catheters is often represented by French No, such as 6 F or 7 F. French No is the number of length in millimeter of an outer perimeter of the catheter. The shape and structure of special catheters are relatively complex. Their medical functions performed are also various, for example, double cavity single balloon catheter, balloon catheters for coronary artery angioplasty. Other common catheters comprise guiding catheters, coaxial catheters, micro catheters, direction controlled catheters, catheters for cutting atrial septum, catheters for capturing blood clot, rotablator, rotational atherectomy catheter, mapping electrode catheter, radiofrequency ablation catheter (also known as a large tip catheter), pacemaker electrode catheter and the like. The coronary artery angioplasty (PTCA) catheter is an important catheter comprising PTCA guiding catheter, PTCA dilatation catheter, and guide wires. The tube wall of guiding catheter comprises three layers: an outer layer of polyurethane or polyethylene, a middle layer of an epoxy resin-fiber network or metal network, an inner layer of smooth Teflon. The metal network or spiral structure in the middle of the catheter are often termed as a hypotube, which ensures some strength of the catheter and maintains the flexibility, formed by precisely laser cutting process.
The guide wire can guide the catheter into blood vessels or other lumen percutaneously. Further, it can help the catheter entering thin branches of blood vessels or other diseased cavity gaps, and changing catheters during operation. After the guide wire entering human body, under the guiding of the guide wire, the catheter can reach a desired location by the guide wire. Then drugs or special device, such as heart stent can be delivered by the catheter. The basic structure of the guide wire consists of an inner hard core and an outer closely wrapped winding wire. The inner core guide wire is known as an axial fiber, ensuring the hardness of the guide wire. The tip is converging, that is, the tip is gradually tapered, causing the tip softer. The outside of the axial fiber is formed by wrapping stainless steel spring coil winding wire.
Shape memory alloy (SMA) possesses special properties such as shape memory, superelasticity. The martensite phase change of a shape memory alloy can be controlled by the temperature and stress of materials so as to achieve the special mechanical properties of materials. Thus, it can be used in the condition of intelligent control, such as an active control and a passive control. Springs of shape memory alloy are effective control elements for an active vibration control and a passive vibration control, which can be widely applied to the fields of spaceflight, industrial control and medical treatment.
Compared with common means in the art such as surgery, chemotherapy and radiotherapy, the photodynamic therapy of tumors possess several advantages, such as less injury, less toxicity, better targeting and improved feasibility. However, the difficulty is how to transmit the light into the human body through human body blood vessels. The earlier applications 201611234625X and 2016214560291 filed by the applicant recite that the light can be transmitted to the location of lesion of the body by very thin optical fiber guide wire passing through blood vessel in human body. The diameter of an optical fiber guide wire is just hundreds of microns. Generally, the largest diameter is about 2 mm, the smallest diameter is only about 100 μm. However, its length is about in the range of 1.5 to 2 m. Thus, if inserting such thin and long optical fiber guide wire into human body, the structure of optical fiber guide wires should be good enough. Therefore, how to insert the optical fiber core wire and improve the strength and safety of the optical fiber guide wire are very important.